Imidazolyl and triazolyl compounds, compositions containing them and methods of using them as plant fungicidal and growth regulating agents

ABSTRACT

Fungicidal or plant growth regulating compounds of the formula &lt;IMAGE&gt;   wherein each of R1 and R2, which may be the same or different, is unsubstituted or methyl-substituted C3-6 cycloalkyl, unsubstituted or halo-substituted C1-6 alkyl or unsubstituted or halo-, C1-4 alkyl-, C1-4 alkoxy-, phenyl- or nitro-substituted phenyl, and Y is =N- or =CH-; or an acid addition salt or metal complex thereof.

This invention relates to imidazole and triazole compounds having fungicidal and plant growth regulating activity, to fungicidal and plant growth regulating compositions containing them and to a method of combating fungal infections in, or regulating the growth of, plants using them.

The compounds have the general formula (I) ##STR2## wherein each of R¹ and R², which may be the same or different, is unsubstituted or alkyl-substituted cycloalkyl (e.g. cyclopentyl, cyclohexyl or methylcyclohexyl), unsubstituted or halo-substituted alkyl (e.g. trichloromethyl) or unsubstituted or halo-, alkyl-, alkoxy-, phenyl- or nitro-substituted phenyl; and Y is ═N-- or ═CH--; or an acid addition salt or metal complex thereof.

The compounds of the invention contain chiral centres. The compounds are generally obtained in the form of racemic mixtures. However, these and other mixtures can be separated into the individual isomers by methods known in the art. The compounds also form geometrical isomers; mixtures of these isomers can be separated by methods known in the art.

The alkyl and alkoxy groups can be straight or branched chain groups having 1 to 6, e.g. 1 to 4 carbon atoms; examples are methyl, ethyl, propyl (n- or iso-propyl), butyl (n-, sec-, iso- or t-butyl), methoxy and ethoxy. The halogen atoms can be fluorine, chlorine, bromine, or iodine. Examples of the substituted phenyl groups are o-, m- or p-chlorophenyl, 2,4- or 2,6-dichlorophenyl, o-, m- or p-fluorophenyl, o-, m- or p-bromophenyl, o-, m- or p-methoxyphenyl, 2,4-dimethoxyphenyl, o-, m- or p-ethoxyphenyl, o-, m- or p-nitrophenyl, o-, m- or p-methylphenyl and p-phenylphenyl (p-biphenylyl). Suitably the phenyl group is unsubstituted or is substituted with 1, 2 or 3 substituents as defined above.

The salts can be salts with inorganic or organic acids e.g. hydrochloric, nitric, sulphuric, acetic, p-toluenesulphonic or oxalic acid.

Examples of the compounds of the invention are shown in Table I.

                  TABLE I                                                          ______________________________________                                         COM-                                                                           POUND                              MELTING                                     NO      R.sup.1 R.sup.2     Y      POINT (°C.)                          ______________________________________                                         1       t-Bu    o-Cl--C.sub.6 H.sub.4                                                                      ═N--                                                                              167-168                                     2       t-Bu    o-Cl--C.sub.6 H.sub.4                                                                      ═N--                                                                              163-167                                     3       t-Bu    p-Cl--C.sub.6 H.sub.4                                                                      ═N--                                                                              163-164                                     4       t-Bu    p-Cl--C.sub.6 H.sub.4                                                                      ═N--                                                                              168-169                                     5       i-Pr    p-Cl--C.sub.6 H.sub.4                                                                      ═N--                                                                              165-166                                     6       i-Pr    p-Cl--C.sub.6 H.sub.4                                                                      ═N--                                                                              151-152                                     7       t-Bu    C.sub.6 H.sub.5                                                                            ═N--                                                                              172-174                                     8       t-Bu    C.sub.6 H.sub.5                                                                            ═N--                                                                              169-170                                     9       t-Bu    p-F--C.sub.6 H.sub.4                                                                       ═N--                                                                              184-186                                     10      t-Bu    p-F--C.sub.6 H.sub.4                                                                       ═N--                                                                              180-181                                     11      t-Bu    p-MeO--C.sub.6 H.sub.4                                                                     ═N--                                                                              157-158                                     12      t-Bu    p-MeO--C.sub.6 H.sub.4                                                                     ═N--                                                                              166-167                                     13      t-Bu    o-MeO--C.sub.6 H.sub.4                                                                     ═N--                                                                              168-170                                     14      t-Bu    o-MeO--C.sub.6 H.sub.4                                                                     ═ N--                                                                             gum                                         15      i-Pr    p-MeO--C.sub.6 H.sub.4                                                                     ═N--                                                                              127-128                                     16      i-Pr    p-MeO--C.sub.6 H.sub.4                                                                     ═N--                                                                              136-138                                     ______________________________________                                          Compounds 1 and 2 are diastereoisomers of each other, as are Compounds 3       and 4, 5 and 6, 7 and 8, 9 and 10, 11 and 12, 13 and 14 and 15 and 16.   

The compounds (and the salts and complexes) of the invention may be made by reducing (preferably at 0° to 100° C. and for 1 to 12 hours) a diketone of general formula (II): ##STR3## wherein Y, R¹ and R² are as defined above, and Z¹ and Z² are both C═O, or a salt or metal complex thereof, with for example a metal hydride reducing agent (e.g. lithium aluminium hydride, sodium borohydride or aluminium isopropoxide) in an inert polar solvent (e.g. water or ethanol).

The diketones wherein Y is ═N-- are the subject of British Patent Application No. 50936/77, the disclosure of which document being incorporated herein by reference.

The starting materials for the above process may be made by reacting imidazole or 1,2,4-triazole or a salt thereof with the appropriate dihalo-δ-diketone of general formula (III): ##STR4## wherein R¹, R², Z¹ and Z² are as defined above for the compound of general formula (II), and each of the groups X¹ and X², which may be the same or different, is halogen (e.g. chlorine or bromine). This process is suitably carried out by heating the reactants together in a suitable solvent (such as acetonitrile, tetrahydrofuran or dimethylformamide); preferably it is performed by reacting the sodium salt of triazole or imidazole with a dibromo-δ-diketone in for example boiling dimethylformamide. The product can be isolated by pouring the reaction mixture into water and recrystallising the product from a convenient solvent.

The dihalo-β-diketone starting materials may be made by halogenation (e.g. bromination) of a compound of general formula (IV):

    R.sup.1 --Z.sup.1 --CH═CH--Z.sup.2 --R.sup.2           (IV)

wherein R¹, R², Z¹ and Z² are as defined above for the compound of general formula (II). Suitable brominating agents are bromine itself, N-bromosuccinimide and pyridinium hydrobromide perbromide.

The compounds of general formula (IV) may be made by methods set out in the literature.

The compounds of general formula (II) may also be made by reacting a compound of general formula (V): ##STR5## where Y and R¹ are as defined above and Z¹ is C═O, with a compound of general formula (VI):

    OHC--Z.sup.2 --R.sup.2

where R² is as defined above and Z² is C═O, in the presence of a base (e.g. sodium methoxide or N-methylaniline magnesium bromide) to give a compound of general formula (VII): ##STR6## wherein Y, R¹ and R² are as defined above and Z¹ and Z² are C═O. The compound of general formula (VII) can be dehydrated under standard conditions to give the compound of general formula (II). The dehydration is suitably achieved by using p-toluene sulphonyl chloride in pyridine.

The compounds of general formula (V) and (VI) may be made by methods set out in the literature.

The salts and metal complexes of the compounds of general formula (I) can be prepared from the latter in known manner. For example, the complexes can be made by reacting the uncomplexed compound with a metal salt in a suitable solvent.

The compounds are active fungicides, particularly against the diseases:

Pyricularia oryzae on rice

Puccinia recondita, Puccinia striiformis and other rusts on wheat, Puccinia hordei, Puccinia striiformis and other rusts on barley, and rusts on other hosts e.g. coffee, apples, vegetables and ornamental plants

Plasmopara viticola on vines

Erysiphe graminis (powdery mildew) on barley and wheat and other powdery mildews on various hosts such as Helminthosporium spp. on cereals, Sphaerotheca fuliginea on cucurbits (e.g. cucumber), Podosphaera leucotricha on apples and Uncinula necator on vines

Cercospora arachidicola on peanuts and other Cercospora species on for example sugar beet, bananas and soya beans Botrytis cinerea (grey mould) on tomatoes, strawberries, vines and other hosts

Phytophthora infestans (blight) on tomatoes

Venturia inaequalis (scab) on apples

Some of the compounds have also shown a broad range of activities against fungi in vitro. They have activity against various post-harvest diseases on fruit (e.g. Penicillium digatatum and italicum on oranges and Gloeosporium musarum on bananas). Further some of the compounds are active as seed dressings against: Fusarium spp., Septoria spp., Tilletia spp. (i.e. bunt, a seed borne disease of wheat), Ustilago spp., Helminthosporium spp. on cereals, Rhizoctonia solani on cotton and Corticium sasakii on rice.

The compounds have plant growth regulating activities.

The plant growth regulating effects of the compounds are manifested as for example a stunting or dwarfing effect on the vegetative growth of woody and herbaceous mono- and di-cotyledonous plants. Such stunting or dwarfing may be useful, for example, in peanuts, cereals and soya bean where reduction in stem growth may reduce the risk of lodging and may also permit increased amounts of fertiliser to be applied. The stunting of woody species is useful in controlling the growth of undergrowth under power lines etc. Compounds which induce stunting or dwarfing may also be useful in modifying the stem growth of sugar cane thereby increasing the concentration of sugar in the cane at harvest; in sugar cane, the flowering and ripening may be controllable by applying the compounds. Stunting of peanuts can assist in harvesting. Growth retardation of grasses can help maintenance of grass swards. Examples of suitable grasses are Stenotaphrum secundatum (St. Augustine grass), Cynosurus cristatus, Lolium multiflorum and perenne,

Agrostis tenuis, Cynoden dactylon (Bermuda grass), Dactylis glomerata, Festuca app. (e.g. Festuca rubra) and Poa spp. (e.g. Poa pratense). The compounds may stunt grasses without significant phytotoxic effects and without deleteriously affecting the appearance (particularly the colour) of the grass; this makes such compounds attractive for use on ornamental lawns and on grass verges. They may also have an effect on flower head emergence in for example grasses. The compounds can also stunt weed species present in the grasses; examples of such weed species are sedges (e.g. Cyperus spp.) and dicotyledonous weeds (e.g. daisy, plantain, knotweed, speedwell, thistle, docks and ragwort). The growth of non-crop vegetation (e.g. weeds or cover vegetation) can be retarded thus assisting in the maintenance of plantation and field crops. In fruit orchards, particularly orchards subject to soil erosion, the presence of grass cover is important. However excessive grass growth requires substantial maintenance. The compounds of the invention could be useful in this situation as they could restrict growth without killing the plants which would lead to soil erosion; at the same time the degree of competition for nutrients and water by the grass would be reduced and this could result in an increased yield of fruit. In some cases, one grass species may be stunted more than another grass species; this selectivity could be useful for example for improving the quality of a sward by preferential suppression of the growth of undesirable species.

The dwarfing may also be useful in miniaturising ornamental, household, garden and nursery plants (e.g. poinsettias, chrysanthemums, carnations, tulips and daffodils).

As indicated above, the compounds can also be used to stunt woody species. This property can be used to control hedgerows or to shape fruit trees (e.g. apples). Some coniferous trees are not significantly stunted by the compounds so the compounds could be useful in controlling undesirable vegetation in conifer nurseries.

The plant growth regulating effect may (as implied above) manifest itself in an increase in crop yield.

In the potato, vine control in the field and inhibition of sprouting in the store may be possible.

Other plant growth regulating effects caused by the compounds include alteration of leaf angle and promotion of tillering in monocotyledonous plants. The former effect may be useful for example in altering the leaf orientation of, for example, potato crops thereby letting more light into the crops and inducing an increase in phytosynthesis and tuber weight. By increasing tillering in monocotyledonous crops (e.g. rice), the number of flowering shoots per unit area may be increased thereby increasing the overall grain yield of such crops. In grass swards an increase in tillering could lead to a denser sward which may result in increased resilience in wear.

The treatment of plants with the compounds can lead to the leaves developing a darker green colour.

The compounds may inhibit, or at least delay, the flowering of sugar beet and thereby may increase sugar yield. They may also reduce the size of sugar beet without reducing significantly the sugar yield thereby enabling an increase in planting density to be made. Similarly in other root crops (e.g. turnip, swede, mangold, parsnip, beetroot, yam and cassava) it may be possible to increase the planting density.

The compounds could be useful in restricting the vegetative growth of cotton thereby leading to an increase in cotton yield.

The compounds may be useful in rendering plants resistant to stress since the compounds can delay the emergence of plants grown from seed, shorten stem height and delay flowering; these properties could be useful in preventing frost damage in countries where there is significant snow cover in the winter since then the treated plants would remain below the snow cover during the cold weather. Further the compounds may cause drought or cold resistance in certain plants.

In carrying out the plant growth regulating method of the invention, the amount of compound to be applied to regulate the growth of plants will depend upon a number of factors, for example the particular compound selected for use, and the identity of the plant species whose growth is to be regulated. However, in general an application rate of 0.1 to 15, preferably 0.1 to 5, kg per hectare is used. However, on certain plants even application rates within these ranges may give undesired phytotoxic effects. Routine tests may be necessary to determine the best rate of application of a specific compound for any specific purpose for which it is suitable.

The compounds may be used as such for fungicidal and plant growth regulating purposes but are more conveniently formulated into compositions for such usage. The invention thus provides also a fungicidal or plant growth regulating composition comprising a compound of general formula (I) or a salt or complex as hereinbefore defined, and a carrier or diluent.

It also provides a method of combating fungal infections in, or regulating the growth of, a plant which method comprises applying to the plant, to seed of the plant or to the locus of the plant or seed a compound or salt or complex thereof as hereinbefore defined.

The compounds, salts and complexes can be applied in a number of ways, for example they can be formulated or unformulated, directly to the foliage of a plant, or they can be applied also to bushes and trees, to seeds or to other medium in which plants, bushes or trees are growing or are to be planted, or they can be sprayed on, dusted on or applied as a cream or paste formulation, or they can be applied as a vapour. Application can be to any part of the plant, bush or tree, for example to the foliage, stems, branches or roots, or to soil surrounding the roots, or to the seed before it is planted.

The term "plant" as used herein includes seedlings, bushes and trees. Furthermore, the fungicidal method of the invention includes preventative, protectant, prophylactic and eradicant treatment.

The compounds are preferably used for agricultural and horticultural purposes in the form of a composition. The type of composition used in any instance will depend upon the particular purpose envisaged.

The compositions may be in the form of dusting powders or granules comprising the active ingredient and a solid diluent or carrier, for example fillers such as kaolin, bentonite, keiselguhr, dolomite, calcium carbonate, talc, powdered magnesia, Fuller's earth, gypsum, Hewitt's earth, diatomaceous earth and China clay. Such granules can be preformed granules suitable for application to the soil without further treatment. These granules can be made either by impregnating pellets of filler with the active ingredient or by pelleting a mixture of the active ingredient and powdered filler. Compositions for dressing seed, for example, may comprise an agent (for example a mineral oil) for assisting the adhesion of the composition to the seed; alternatively the active ingredient can be formulated for seed dressing purposes using an organic solvent (for example N-methylpyrrolidone or dimethylformamide).

The compositions may also be in the form of dispersible powders, granules or grains comprising a wetting agent to facilitate the dispersion in liquids of the powder or grains which may contain also fillers and suspending agents.

The aqueous dispersions or emulsions may be prepared by dissolving the active ingredient(s) in an organic solvent optionally containing wetting, dispersing or emulsifying agent(s) and then adding the mixture to water which may also contain wetting, dispersing or emulsifying agent(s). Suitable organic solvents are ethylene dichloride, isopropyl alcohol, propylene glycol, diacetone alcohol, toluene, kerosene, methylnaphthalene, the xylenes, trichloroethylene, furfuryl alcohol, tetrahydrofurfuryl alcohol, and glycol ethers (e.g. 2-ethoxyethanol and 2-butoxyethanol).

The compositions to be used as sprays may also be in the form of aerosols wherein the formulation is held in a container under pressure in the presence of a propellant, e.g. fluorotrichloromethane or dichlorodifluoromethane.

The compounds can be mixed in the dry state with a pyrotechnic mixture to form a composition suitable for generating in enclosed spaces a smoke containing the compounds.

Alternatively, the compounds may be used in a microencapsulated form.

By including suitable additives, for example additives for improving the distribution, adhesive power and resistance to rain on treated surfaces, the different compositions can be better adapted for various utilities.

The compounds can be used as mixtures with fertilisers (e.g. nitrogen-, potassium- or phosphorus-containing fertilisers). Compositions comprising only granules of fertiliser incorporating, for example coated with, the compound, are preferred. Such granules suitably contain up to 25% by weight of the compound. The invention therefore also provides a fertiliser composition comprising the compound of general formula (I) or a salt or metal complex thereof.

The compositions may also be in the form of liquid preparations for use as dips or sprays which are generally aqueous dispersions or emulsions containing the active ingredient in the presence of one or more surfactants e.g. wetting agent(s), dispersing agent(s), emulsifying agent(s) or suspending agent(s). These agents can be cationic, anionic or non-ionic agents. Suitable cationic agents are quaternary ammonium compounds, for example cetyltrimethylammonium bromide.

Suitable anionic agents are soaps, salts of aliphatic monoesters of sulphuric acid (for example sodium lauryl sulphate), and salts of sulphonated aromatic compounds (for example sodium dodecylbenzenesulphonate, sodium, calcium or ammonium lignosulphonate, butylnaphthalene sulphonate, and a mixture of sodium diisopropyl- and triisopropyl-naphthalene sulphonates).

Suitable non-ionic agents are the condensation products of ethylene oxide with fatty alcohols such as oleyl or cetyl alcohol, or with alkyl phenols such as octyl- or nonyl-phenol and octylcresol. Other non-ionic agents are the partial esters derived from long chain fatty acids and hexitol anhydrides, the condensation products of the said partial esters with ethylene oxide, and the lecithins. Suitable suspending agents are hydrophilic colloids (for example polyvinylpyrrolidone and sodium carboxymethylcellulose), and the vegetable gums (for example gum acacia and gum tragacanth).

The compositions for use as aqueous dispersions or emulsions are generally supplied in the form of a concentrate containing a high proportion of the active ingredient(s), the concentrate to be diluted with water before use. These concentrates often should be able to withstand storage for prolonged periods and after such storage be capable of dilution with water in order to form aqueous preparations which remain homogeneous for a sufficient time to enable them to be applied by conventional spray equipment. The concentrates may conveniently contain up to 95%, suitably 10-85%, for example 25-60%, by weight of the active ingredient(s). These concentrates suitably contain organic acids (e.g. alkaryl or aryl sulphonic acids such as xylenesulphonic acid or dodecylbenzenesulphonic acid) since the presence of such acids can increase the solubility of the active ingredient(s) in the polar solvents often used in the concentrates. The concentrates suitably contain also a high proportion of surfactants so that sufficiently stable emulsions in water can be obtained. After dilution to form aqueous preparations, such preparations may contain varying amounts of the active ingredient(s) depending upon the intended purpose, but an aqueous preparation containing 0.0005% or 0.01% to 10% by weight of active ingredient(s) may be used.

The compositions of this invention can comprise also other compound(s) having biological activity, e.g. compounds having similar or complementary fungicidal or plant growth regulating activity or compounds having herbicidal or insectidical activity.

The other fungicidal compound can be for example one which is capable of combating ear diseases of cereals (e.g. wheat) such as Septoria, Gibberella and Helminthosporium spp., seed and soil borne diseases and downy and powdery mildews on grapes and powdery mildew and scab on apple etc. These mixtures of fungicides can have a broader spectrum of activity than the compound of general formula (I) alone; further the other fungicide can have a synergistic effect on the fungicidal activity of the compound of general formula (I). Examples of the other fungicidal compounds are imazalil, benomyl, carbendazim (BCM), thiophanate-methyl, captafol, captan, sulphur, dithiocarbamates, carbathiins, copper oxychloride, triforine, dodemorph, tridemorph, dithianon, pyrazophos, binapacryl, quinomethionate, panoctine, furalaxyl, aluminium trio(ethyl phosphonate), DPX3217, ethirimol, dimethirimol, bupirimate, chlorothalonil, Chevron RE 20615, vinclozolin, procymidone, iprodione and metaxanine.

The other plant growth regulating compound can be one which controls weeds or seedhead formation, improves the level or longevity of the plant growth regulating activity of the compounds of general formula (I), selectively controls the growth of the less desirable plants (e.g. grasses) or causes the compound of general formula (I) to act faster or slower as a plant growth regulating agent. Some of these other agents will be herbicides. Examples of suitable agents are the gibberellins (e.g. GA₃, GA₄ or GA₇), the auxins (e.g. indoleacetic acid, indolebutyric acid, naphthoxyacetic acid or naphthylacetic acid), the cytokinins (e.g. kinetin, diphenylurea, benzimidazole, benzyladenine or BAP), phenoxyacetic acids (e.g. 2,4-D or MCPA), substituted benzoic acids (e.g. TIBA), morphactins (e.g. chlorfluorecol), maleic hydrazide, glyphosate, glyphosine, long chain fatty alcohols and acids (e.g. Off Shoot O or Off Shoot T), dikegulac, Sustar, Embark, substituted quaternary ammonium and phosphonium compounds (e.g. CCC or Phosfon-D), Ethrel, carbetamide, Racuza, Alar, asulam, abscissic acid, isopyrimol, RH531, hydroxybenzonitriles (e.g. bromoxynil), Avenge, Suffix or Lontrel.

The following Examples illustrate the invention; the temperatures are given in degrees Centigrade (°).

EXAMPLE 1

Stage 1--A solution of 4'-chlorophenylglyoxal (15 g) and 1-(1,2,4-triazol-1-yl)-3-methylbutan-2-one (18.6 g) in methanol (100 ml) was treated dropwise with 2% sodium methoxide in methanol, until a green colour developed. The solution was then scratched to induce precipitation of a white solid which was filtered and washed with methanol. The filtrate and washings were treated with further methoxide to obtain a second crop of white solid which was air dried. The white solid (23.5 g; yield 75%) was 3-(1,2,4-triazol-1-yl)-1-(p-chlorophenyl)-5-methylhexan-1,4-dion-2-ol, m.p. 184°-185° C.

Stage 2--The white solid was then dissolved with stirring in toluene-4-sulphonyl chloride (15.5 g) in pyridine (100 ml). After standing at room temperature for 24 hours, the now dark brown solution was poured on to a mixture of 2 M-hydrochloric acid and crushed ice (1 liter). The acid mixture was then extracted with diethyl ether (3×200 ml) and the extract was then dried (MgSO₄) and evaporated to give an orange solid (14.7 g; yield 67%). The solid was recrystallised from methanol to give 3-(1,2,4-triazol-1-yl)-1-(p-chlorophenyl)-5-methylhex-2-en-1,4-dione, m.p. 128°-129.5°.

Stage 3--A suspension in methanol (50 ml) of the product (1 g) of Stage 2 was treated with stirring with sodium borohydride (0.25 g). The borohydride was added to a stirred suspension of the product (1 g) of Stage 2 in methanol (50 ml). When the effervescence had ceased (the reaction was exothermic), thin layer chromatography (TLC: silica gel/ethyl acetate) showed no starting material and 2 new spots. The methanol solution was then poured into 2 M-hydrochloric acid (100 ml) and the resultant solution extracted with ethyl acetate to give a gum which was purified by TLC (silica gel/ethyl acetate) to give two main products (0.3 g of each) as gums which solidified on trituration with diethyl ether. The products were found to be diastereoisomers of each other. One (Compound 5) had a melting point of 165°-166° while the other (Compound 6) had a melting point of 151°-152°.

EXAMPLE 2

The compounds were tested against a variety of foliar fungal diseases of plants. The technique employed was as follows.

The plants were grown in John Innes Potting Compost (No. 1, or Seed, as appropriate) in 4 cm diameter minipots. A layer of fine sand was placed at the bottom of the pot to facilitate uptake of test compound by the roots.

The test compounds were formulated either by bead-milling with aqueous Dispersol T or as a solution in acetone/ethanol which was diluted to the required concentration immediately before use. For the foliage diseases, 100 p.p.m. a.i. suspensions were sprayed on to the foliage and applied to the roots of the same plant via the soil. (Sprays were applied to maximum retention, and root drenches to a final concentration equivalent to approximately 40 ppm a.i./dry soil). Tween 20, to give a final concentration of 0.1%, was added when the sprays were applied to the cereals.

For most of the tests, the test compound was applied to the soil (roots) and to the foliage (by spraying) one or two days before the plant was inoculated with the diseases. An exception was the test on Erysiphe graminis, in which the plants were inoculated 24 hours before treatment. After inoculation, the plants were put into an appropriate environment to allow infection to take place and then incubated until the disease was ready for assessment. The period between inoculation and assessment varied from 4 to 14 days according to the disease and environment.

The disease control was recorded by the following grading:

4=No disease

3=0-5%

2=6-25%

1=26-60%

0=>60%

The results are shown in Table II.

                                      TABLE II                                     __________________________________________________________________________          PUC-                                      CERCO-                          COM- CINIA        PIRI- PLASMO-                                                                               PHY-            SPORA                           POUND                                                                               RE-   ERYSIPHE                                                                              CULARIA                                                                              PARA   TOPHTHORA                                                                               BOTRYTIS                                                                              ARACHIDI-                                                                              VENTURIA                NUM- CONDITA                                                                              GRAMINIS                                                                              ORYZAE                                                                               VITICOLA                                                                              INFESTANS                                                                               CINEREA                                                                               COLA    INEQUALIS               BER  (WHEAT)                                                                              (BARLEY)                                                                              (RICE)                                                                               (VINE) (TOMATO) (TOMATO)                                                                              (PEANUT)                                                                               (APPLE)                 __________________________________________________________________________     1    3     4      3     0      0        3      2                               2    3     4      2     0      0        2                                      3    3     4      0     0      0        0      1                               4    4     4      0     0      0        0      0                               5    0     4            4      0        2              0                       6    0     4      0     2      0        1      2                               7    3     4      0     0      1        0      0       0                       8    4     4      0            0        1      3                               9    3     4      1     0      0        2      0       0                       10   3     4      1     0      0        1      1       0                       13   4     4      0     0      0               1       0                       14   3     4            0      0        2      0       0                       15   0     4      2     0      0        0      0       0                       __________________________________________________________________________

EXAMPLE 3

This Example illustrates the plant growth regulating properties of the compounds. The compounds were applied in the form of a 4000 ppm solution in distilled water and the solution was then applied to the foliage of young seedlings of various plants. The experiments were replicated twice. After 12 or 13 days from treatment, the plants were assessed for plant growth regulating effects and phytotoxic symptoms.

Table III shows the stunting effect of the compounds on the vegetative growth using the following grading:

1=0-30% retardation

2=31-75% retardation

3=>75% retardation

If no figure is given, the compound was substantially inactive as a stunting agent. Additional plant growth regulating properties are indicated as follows:

G=darker green leaf colour

A=apical effect

T=tillering effect

                                      TABLE III                                    __________________________________________________________________________     COM-                      CYN- DAC-                                            POUND            SUG-                                                                               AGROS-                                                                              ODON TYLIS                        TO-                NUM-     COT-    AR  TIS  DAC- GLOM-     BAR-         FRENCH                                                                               MA-                BER  SOYA                                                                               TON RAPE                                                                               BEET                                                                               TENUIS                                                                              TYLON                                                                               ERATA                                                                               WHEAT                                                                               LEY RICE                                                                               MAIZE                                                                               BEAN  TO                 __________________________________________________________________________     1    3GAT                                                                               3GA 3GA 3GA 2    2    2    3GT  3GT 3G  3G   3GA   3A                 2            2G  2G  1    1                           3GA   3GT                3    2GT         2   2G   2G   1                      2GA   2GT                4    2GAT    2   1   2G   2G   1                 1    2GA   3G                 5    1T      2G  2                                    2GA   2                  6    2GAT    1G      1    1                           2GA   2                  7    2       G                                        2G    T                  8    3GT 1   1G  1G                 2GT      1   3    3A    3A                 9    1G      1G                                       3A    1                  10   3GT 1   2G  2G                 1G       1   2G   3A    2A                 11   1GT 1   1G  1G                              1    3GA   2                  13   1G          G                                    3A    1                  14                                  T    T   T   1    2     1                  15   2           1        1                           1     1T                 16   2       1G  1        1                           2A    2AT                __________________________________________________________________________ 

We claim:
 1. A compound of general formula (I) ##STR7## wherein each of R¹ and R², which may be the same or different, is unsubstituted or methyl-substituted C₃₋₆ cycloalkyl, unsubstituted or halo-substituted C₁₋₆ alkyl or unsubstituted or halo-, C₁₋₄ alkyl-, C₁₋₄ alkoxy-, phenyl- or nitro-substituted phenyl, and Y is ═N-- or ═CH--; or a fungicidal or plant growth regulating acid addition salt or metal complex thereof wherein said salt is a salt of hydrochloric acid, nitric acid, sulphuric acid, acetic acid, p-toluene sulphonic acid or oxalic acid and said complex is prepared by reacting the uncomplexed compound of formula (I) with a metal salt in a suitable solvent.
 2. A compound as claimed in claim 1 wherein R¹ is propyl or butyl.
 3. A compound as claimed in claim 2 wherein R¹ is i-propyl or t-butyl.
 4. A compound as claimed in claim 1 wherein R² is phenyl, monochlorophenyl, monofluorophenyl or monomethoxyphenyl.
 5. A compound as claimed in claim 4 wherein R² is o- or p-chlorophenyl, p-fluorophenyl, or o- or p-methoxyphenyl.
 6. A fungicidal or plant growth regulating composition consisting essentially of a fungicidally or plant growth regulating effective amount of a compound, salt or complex as claimed in claim 1, and a carrier or diluent.
 7. A method of combating fungal infections in, or regulating the growth of, a plant, the method consisting essentially of the step of applying to the plant, to seed of the plant or to the locus of the plant or seed a fungicidally or plant growth regulating effective amount of a compound, salt or complex as claimed in claim
 1. 8. A compound of general formula (I) ##STR8## wherein each of R¹ and R², which may be the same or different, is unsubstituted or methyl-substituted C₃₋₆ cycloalkyl, unsubstituted or halo-substituted C₁₋₆ alkyl or unsubstituted or halo-, C₁₋₄ alkyl-, C₁₋₄ alkoxy-, phenyl- or nitro-substituted phenyl, and Y is ═N-- or ═CH--; or a fungicidal or plant growth regulating acid addition salt of hydrochloric acid, nitric acid, sulphuric acid, acetic acid, p-toluene sulphonic acid or oxalic acid. 